Conventional control valves used in low pressure fluid systems are not ideal when actuation of the valve requires a minimum pressure drop, or for applications where the fluid stream cannot be used as the medium. Many control valves are actuated based on a pressure differential that causes the valve to close above a pressure set point and open below the same pressure set point. Thus, valve actuation based on a pressure point differential typically does not allow for consistent operation across a wide range of operating pressures of the system, which may occur in water filtration systems during installations, or through applications with limited and/or no power. In addition, most differential pressure valves or direct acting valves use a sealing mechanism attached to a piston within the valve to actuate the valve. Therefore, valves actuated by differential pressure, rather than actuation from a pressure that changes from high to low, require larger valve sizes, which can be less economical.
Many control valves also require use of external components disposed outside of a valve housing, such a solenoid valve having an external electrical connection. A solenoid is necessary to move a plunger, which creates a small opening and causes pressure through the opening to actuate the valve seal. Solenoid valves typically require a constant flow of electrical current to remain open because the electromagnetic field dissipates and the valve returns to its original or closed position once the current is stopped. Other control valves, such as check valves, pressure relief valves, and needle valves, also require external components to operate, causing increases in manufacturing costs. Further, many conventional pressure relief valves do not operate within a single contained housing. For example, pressure relief valves typically use other external components to operate, and may operate externally from the valve itself. As a result, the valve often needs to be adjusted depending on different operating pressures required by the system. Many control valves also include multiple chambers that need to be pressurized separately, thereby increasing system setup times. In addition, many control valves require electrical power to actuate the valve and, therefore, do not function using system-based parameters, such as pressure, which can change with the manual opening and closing of the system, thus creating higher operational costs. Lastly, conventional control valves typically allow backflow of the system fluid when in the closed position, which can cause damage to membranes in the system, if present.
One known system discloses a hydraulic control valve comprising a housing fitted with an inlet port, an outlet port, and a sealing port that divides the housing into an inlet chamber and an outlet chamber. A stem is connected to a diaphragm and is axially displaced within the housing. The diaphragm separates the housing into a first control chamber and a second control chamber. A control port is connected to the first control chamber and a hydraulic or pneumatic control signal is introduced by a controller to the control port to close the valve. The hydraulic or pneumatic control signal is in communication with a power source, which generates an applied force to a rigid disc mounted to the top surface of the diaphragm, thereby closing the valve.
Another system discloses a valve mechanism including a valve body and bonnet structure defining a tapered valve chamber that receives a tapered plug member that is operated by linear and rotary components of movement to achieve valve operation. An external component provided in the form of an externally adjustable plug is provided by the valve mechanism to enable the position of the plug element to be adjusted relative to the inlet and outlet flow passages defined by the valve body. A predetermined pressure differential across the sealing elements of the valve is required to compensate for volumetric changes as the valve element is seated and unseated.
Another system provides a check valve mechanism including a valve body and valve seat assembly having noncircular, eccentrically located hinge pin receptacles. Hinge pins are supported in the receptacles that support a check valve disc in such a manner that both opening and closing movements have components of rotary and linear disc movement relative to the hinge pin and valve seat. As the pressure differential across the disc member increases, the disc member moves linearly to open and close the valve. In addition, if the hinge pins are not in engagement with the receptacles, reverse flow of the system fluid is allowed.
Therefore, it would be desirable to provide a system and method that addresses one or more of the needs described above. More particularly, it would be desirable to provide a valve system that does not use external components to operate, like the construction of many existing check valves, pressure relief valves, and needle valves, for example. Rather, a valve that operates without the influence of external components is desirable. It would also be desirable to provide a valve system that uses a pressure set point, as opposed to a differential pressure, to open and close the valve. A valve that needs only one of the valve chambers to be pressurized, while still being able to operate in a consistent fashion regardless of the system pressure level, is also desirable. Finally, it would also be desirable to provide a valve that mechanically functions (i.e., requires no power) with the manual operation of the system (e.g., opening and closing of a faucet) and does not allow backflow of the system fluid when the valve is in the closed position.